阅读说明：本技术 抗蚀剂下层膜形成用组合物 (Composition for forming resist underlayer film ) 是由 绪方裕斗 桥本雄人 田村护 岸冈高广 于 2018-04-27 设计创作，主要内容包括：本发明的课题是提供在曝光时作为防反射膜起作用,并且可以埋入狭窄空间和高长宽比的凹部,进一步相对于过氧化氢水溶液的耐性优异的抗蚀剂下层膜形成用组合物。解决手段是一种抗蚀剂下层膜形成用组合物,其包含树脂、下述式(1a)或式(1b)所示的化合物、和溶剂,相对于上述树脂,含有0.01质量％～60质量％的上述式(1a)或式(1b)所示的化合物。(式中,X表示羰基或亚甲基,l和m各自独立地表示满足3≤l+m≤10的关系式的整数0～5,n表示整数2～5。)<Image he="279" wi="700" file="DDA0002245605080000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention provides a composition for forming a resist underlayer film, which functions as an anti-reflective film during exposure, can be embedded in a recess having a narrow space and a high aspect ratio, and has excellent resistance to an aqueous hydrogen peroxide solution. The composition for forming a resist underlayer film comprises a resin, a compound represented by formula (1a) or (1b), and a solvent, and contains the compound represented by formula (1a) or (1b) in an amount of 0.01 to 60% by mass relative to the resin. (wherein X represents a carbonyl group or a methylene group, l and m each independently represents an integer of 0 to 5 and n represents an integer of 2 to 5, both of which satisfy the relationship of 3. ltoreq. l + m.ltoreq.10.))

1. A resist underlayer film forming composition comprising a resin, a compound represented by formula (1a) or (1b), and a solvent, wherein the compound represented by formula (1a) or (1b) is contained in an amount of 0.01 to 60% by mass relative to the resin,

Wherein X represents a carbonyl group or a methylene group, l and m each independently represent an integer of 0 to 5 satisfying the relational expression of 3. ltoreq. l + m. ltoreq.10, and n represents an integer of 2 to 5.

2. The composition for forming a resist underlayer film according to claim 1, wherein at least one benzene ring in the compound represented by formula (1a) has a phenolic hydroxyl group on 2 or more adjacent carbon atoms of the ring, and wherein a benzene ring in the compound represented by formula (1b) has a phenolic hydroxyl group on 2 or more adjacent carbon atoms of the ring.

3. The resist underlayer film forming composition according to claim 1 or 2, wherein l and m in the compound represented by formula (1a) each represent 3, and n in the compound represented by formula (1b) represents 3.

4. The resist underlayer film forming composition according to any one of claims 1 to 3, wherein the resin is a copolymer having no substituent containing an epoxy ring or an oxetane ring.

5. A method for manufacturing a semiconductor device, comprising the steps of: a step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 4 on a semiconductor substrate having a recess on a surface thereof and capable of forming an inorganic film; forming a resist underlayer film at least in the recessed portion by baking the resist underlayer film forming composition; and forming a resist pattern on the resist underlayer film.

6. The method for manufacturing a semiconductor element according to claim 5, wherein the semiconductor substrate has a trench having a width of 0.001 to 0.10 μm and an aspect ratio of 1 to 100.

7. A pattern forming method includes the steps of: a step of forming a resist underlayer film on a semiconductor substrate having a surface on which an inorganic film can be formed, by using the resist underlayer film forming composition according to any one of claims 1 to 4; forming a resist pattern on the resist underlayer film; dry etching the resist underlayer film using the resist pattern as a mask to expose the inorganic film or the surface of the semiconductor substrate; and a step of wet-etching the inorganic film or the semiconductor substrate with an aqueous hydrogen peroxide solution using the resist underlayer film after the dry etching as a mask, and cleaning the inorganic film or the semiconductor substrate.

Technical Field

The present invention relates to a composition for forming a resist underlayer film that functions as an antireflection film during exposure and can be embedded in a narrow space and a recess portion having a high aspect ratio, and a resist underlayer film (protective film) having excellent resistance to an aqueous hydrogen peroxide solution. Further relates to a method of forming a pattern using the resist underlayer film described above.

Background

A photolithography process is known in which a resist underlayer film is provided between a substrate and a resist film formed on the substrate to form a resist pattern having a desired shape. However, conventional resist underlayer films, for example, resist underlayer films formed from a composition containing an aminoplast-based crosslinking agent, as described in patent document 1 below, have poor resistance to aqueous hydrogen peroxide. Therefore, such a resist underlayer film cannot be used as a mask in a wet etching process using an aqueous hydrogen peroxide solution.

Patent document 2 below describes a composition for forming an underlayer film for lithography, which contains a compound having a protected carboxyl group, a compound having a group capable of reacting with a carboxyl group, and a solvent, or a composition for forming an underlayer film for lithography, which contains a compound having a group capable of reacting with a carboxyl group and a protected carboxyl group, and a solvent, and which does not contain an aminoplast-based crosslinking agent as an essential component. However, patent document 2 does not describe or suggest the resistance of a resist underlayer film formed from the composition to an aqueous hydrogen peroxide solution.

Patent document 3 below describes a pattern forming method using a resist underlayer film having resistance to an alkaline aqueous hydrogen peroxide solution. Further, the composition for forming the resist underlayer film includes a polymer having an epoxy group and a solvent, wherein the polymer has a weight average molecular weight of 1000 to 100,000.

Patent document 4 listed below describes a resist underlayer film forming composition using a polymer having at least 1 sulfur atom in a structural unit. In the case of using a substrate having a recessed portion on the surface thereof in the manufacture of a semiconductor element, a gap-filling material or a planarizing film that can be embedded in the recessed portion of the substrate is required. However, patent document 4 does not describe or suggest the embedding property of the recess.

Patent document 5 listed below describes a resist underlayer film forming composition using a copolymer having a triazine ring and a sulfur atom in the main chain. By using the composition described in patent document 5, a resist underlayer film which functions as an antireflection film at the time of exposure and can further be embedded in a hole (diameter 0.12 μm, depth 0.4 μm) of a semiconductor substrate can be obtained.

Disclosure of Invention

Problems to be solved by the invention

In the manufacture of semiconductor elements, a resist underlayer film satisfying all of the following requirements is required: functions as an antireflection film at the time of exposure; a recess portion which can be embedded in the semiconductor substrate; and has resistance to an aqueous hydrogen peroxide solution, and can be used for pattern formation of a protective film that is resistant to the aqueous hydrogen peroxide solution. However, when the recess is a trench having a narrow space and a high aspect ratio, it is not easy to completely fill the recess with a conventional resist underlayer film forming composition. In addition, it is not easy to perform pattern formation using the conventional resist underlayer film forming composition.

Means for solving the problems

The present invention solves the above problems by applying a resist underlayer film forming composition which comprises a resin, a benzophenone derivative, a diphenylmethane derivative or a benzoic acid derivative having a plurality of phenolic hydroxyl groups, and a solvent, and which contains a specific amount of the benzophenone derivative, the diphenylmethane derivative or the benzoic acid derivative relative to the content of the resin component. Here, the phenolic hydroxyl group means a hydroxyl group bonded to a benzene ring.

The invention of claim 1 is a resist underlayer film forming composition comprising a resin, a compound represented by formula (1a) or formula (1b), and a solvent, wherein the compound represented by formula (1a) or formula (1b) is contained in an amount of 0.01 to 60% by mass relative to the resin.

(wherein X represents a carbonyl group or a methylene group, l and m each independently represents an integer of 0 to 5 and n represents an integer of 2 to 5, both of which satisfy the relationship of 3. ltoreq. l + m.ltoreq.10.)

The compound represented by the above formula (1a) preferably has a phenolic hydroxyl group on 2 or more adjacent carbon atoms of at least one benzene ring, and the compound represented by the above formula (1b) preferably has a phenolic hydroxyl group on 2 or more adjacent carbon atoms of the benzene ring.

In the compound represented by the formula (1a), l and m each represent, for example, 3, and in the compound represented by the formula (1b), n represents, for example, 3.

The resist underlayer film forming composition of the present invention may contain a crosslinking agent. For example, a nitrogen-containing compound having at least 2 nitrogen atoms to which a hydroxymethyl group or an alkoxymethyl group is bonded, an aromatic compound having at least 2 hydroxymethyl groups or alkoxymethyl groups, a compound having at least 2 epoxy groups, or a compound having at least 2 blocked isocyanate groups.

The resist underlayer film forming composition of the present invention may contain a crosslinking catalyst for promoting a crosslinking reaction. For example, a sulfonic acid compound or a carboxylic acid compound, or a thermal acid generator.

The resist underlayer film forming composition of the present invention may further contain a surfactant.

The resin is, for example, a copolymer having no substituent containing an epoxy ring or an oxetane ring.

The invention according to claim 2 is a method for manufacturing a semiconductor device, including the steps of: a step of applying the resist underlayer film forming composition according to claim 1 of the present invention onto a semiconductor substrate having a recess on a surface thereof and capable of forming an inorganic film; forming a resist underlayer film at least in the recessed portion by baking the resist underlayer film forming composition; and forming a resist pattern on the resist underlayer film.

The semiconductor substrate has, for example, a trench having a width of 0.001 to 0.10 μm and an aspect ratio of 1 to 10.

The invention according to claim 3 is a pattern forming method including the steps of: a step of forming a resist underlayer film on a semiconductor substrate, which can have an inorganic film formed on the surface thereof, by using the composition for forming a resist underlayer film according to claim 1 of the present invention; forming a resist pattern on the resist underlayer film; dry etching the resist underlayer film using the resist pattern as a mask to expose the inorganic film or the surface of the semiconductor substrate; and a step of wet-etching the inorganic film or the semiconductor substrate with an aqueous hydrogen peroxide solution using the resist underlayer film after the dry etching as a mask, and cleaning the inorganic film or the semiconductor substrate.

Examples of the aqueous hydrogen peroxide solution include an alkaline aqueous hydrogen peroxide solution containing ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, triethanolamine, or urea, and an acidic aqueous hydrogen peroxide solution containing hydrochloric acid or sulfuric acid. In the case where the aqueous hydrogen peroxide solution is an aqueous alkaline hydrogen peroxide solution containing ammonia, the aqueous alkaline hydrogen peroxide solution is, for example, a mixture of 25 to 30 mass% of an aqueous ammonia solution (a), 30 to 36 mass% of an aqueous hydrogen peroxide solution (B), and water (C), and the volume ratio of the aqueous hydrogen peroxide solution (B) to the aqueous ammonia solution (a): (B) for example, 0.1 to 20.0, and the volume ratio of the water (C) to the aqueous ammonia solution (A): (C) the value of/(A) is, for example, 0.1 to 50.0.

ADVANTAGEOUS EFFECTS OF INVENTION

The resist underlayer film formed from the composition for forming a resist underlayer film of the present invention has resistance to an aqueous hydrogen peroxide solution. Therefore, the resist underlayer film (protective film) formed from the composition for forming a resist underlayer film of the present invention can be used as a mask in an etching process and a cleaning process using an aqueous hydrogen peroxide solution.

The resist underlayer film formed from the resist underlayer film forming composition of the present invention contains a benzophenone derivative or a benzoic acid derivative having a plurality of phenolic hydroxyl groups. By using such a resist underlayer film forming composition, a resist underlayer film which functions as an antireflection film at the time of exposure and can further completely fill a trench having a narrow space and a high aspect ratio can be obtained. In the present specification, "completely embedded" means a state in which voids (gaps) are not observed in the trench by cross-sectional observation using a Scanning Electron Microscope (SEM) as a result of filling the inside of the trench with the resist underlayer film.

Drawings

Fig. 1 is a cross-sectional SEM image of a photoresist pattern formed on a resist underlayer film prepared using the resist underlayer film forming compositions prepared in examples 1 to 12, comparative example 1, and comparative example 2.

Fig. 2 is a schematic view showing a cross section of an SiO2 wafer used in a test of the embeddability (filling ability) of a resist underlayer film into a trench.

Fig. 3 is a cross-sectional SEM image of an SiO2 wafer on which a resist underlayer film was formed on an SiO2 wafer using the resist underlayer film forming compositions prepared in examples 1 to 12, comparative example 1, and comparative example 2.

Detailed Description

The components contained in the resist underlayer film forming composition of the present invention will be described in detail below.

[ resin ]

The resist underlayer film forming composition of the present invention contains a resin as an essential component. The resin is not particularly limited, and examples thereof include polyester, polyether, novolac resin, maleimide resin, acrylic resin, and methacrylic resin. Further, as the resin, a copolymer having no substituent containing an epoxy ring or an oxetane ring is preferably used. Examples of the substituent containing an epoxy ring or an oxetane ring include a glycidyl group and an oxetanyl group.

[ Compound represented by the formula (1a) or (1b) ]

The resist underlayer film forming composition of the present invention contains a compound represented by the above formula (1a) or formula (1b) as an essential component. Examples of the compound represented by the formula (1a) include compounds represented by the following formulae (1a-1) to (1 a-20).

Among the compounds represented by the above formula (1a), for example, 2,3,3 ', 4, 4', 5 '-hexahydroxybenzophenone, 2', 4,4 '-tetrahydroxybenzophenone, 2,3, 4-trihydroxydiphenylmethane, and 2,3,4, 4' -tetrahydroxydiphenylmethane are preferable in terms of being easily available. Among the compounds represented by the above formula (1a), benzophenone derivatives having a plurality of phenolic hydroxyl groups are more preferable in terms of improvement in resistance to aqueous hydrogen peroxide.

Examples of the compound represented by the formula (1b) include compounds represented by the following formulae (1b-1) to (1 b-15).

The resist underlayer film forming composition of the present invention contains, for example, 0.01 to 60% by mass, preferably 0.1 to 20% by mass of the compound represented by the formula (1a) or the formula (1b) relative to the content of the resin. When the content of the compound represented by the formula (1a) or the formula (1b) is less than 0.01% by mass, the effect of the present invention may not be obtained.

The resist underlayer film forming composition of the present invention may contain a crosslinking agent as an optional component together with the above-mentioned compound. The crosslinking agent is also referred to as a crosslinkable compound. The crosslinkable compound is preferably a compound having at least 2 crosslinking-forming substituents, and examples thereof include melamine compounds, substituted urea compounds or aromatic compounds having at least 2 crosslinking-forming substituents such as hydroxymethyl groups and alkoxymethyl groups, compounds having at least 2 epoxy groups, and compounds having at least 2 blocked isocyanate groups. Examples of the alkoxymethyl group include a methoxymethyl group, a 2-methoxyethoxymethyl group and a butoxymethyl group. The crosslinkable compound is more preferably a nitrogen-containing compound having at least 2, for example, 2 to 4 nitrogen atoms to which a hydroxymethyl group or an alkoxymethyl group is bonded. Examples of the nitrogen-containing compound include hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4, 6-tetrakis (methoxymethyl) glycoluril, 1,3,4, 6-tetrakis (butoxymethyl) glycoluril, 1,3,4, 6-tetrakis (hydroxymethyl) glycoluril, 1, 3-bis (hydroxymethyl) urea, 1,3, 3-tetrakis (butoxymethyl) urea, and 1,1,3, 3-tetrakis (methoxymethyl) urea.

Examples of the aromatic compound having at least 2 hydroxymethyl groups or alkoxymethyl groups include 1-hydroxybenzene-2, 4, 6-tricarballyl, 3 ', 5, 5' -tetrakis (hydroxymethyl) -4,4 '-dihydroxybiphenyl (trade name: TML-BP, manufactured by chemical industry Co., Ltd.), 5, 5' - [2,2, 2-trifluoro-1- (trifluoromethyl) ethylene ] bis [ 2-hydroxy-1, 3-benzenedimethanol ] (trade name: TML-BPAF-MF, manufactured by chemical industry Co., Ltd.), 2, 2-dimethoxymethyl-4-tert-butylphenol (trade name: DMOM-PTBP, manufactured by chemical industry Co., Ltd.), 3 ', 5, 5' -tetramethoxymethyl-4, 4' -dihydroxybiphenyl (trade name: TMOM-BP, manufactured by Bunzhou chemical industry Co., Ltd.), bis (2-hydroxy-3-hydroxymethyl-5-methylphenyl) methane (trade name: DM-BIPC-F, manufactured by Asahi organic materials industry Co., Ltd.), bis (4-hydroxy-3-hydroxymethyl-5-methylphenyl) methane (trade name: DM-BIOC-F, manufactured by Asahi organic materials industry Co., Ltd.), and 2, 2-bis (4-hydroxy-3, 5-dihydroxymethylphenyl) propane (trade name: TM-BIP-A, manufactured by Asahi organic materials industry Co., Ltd.).

Examples of the compound having at least 2 epoxy groups include tris (2, 3-epoxypropyl) isocyanurate, 1, 4-butanediol diglycidyl ether, 1, 2-epoxy-4- (epoxyethyl) cyclohexane, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, 2, 6-diglycidyl phenyl glycidyl ether, 1, 3-tris [ p- (2, 3-epoxypropoxy) phenyl ] propane, 1, 2-cyclohexanedicarboxylic acid diglycidyl ester, 4' -methylenebis (N, N-diglycidylaniline), 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, trimethylolethane triglycidyl ether, bisphenol-A-diglycidyl ether, and mixtures thereof, エ ポ リ ー ド (registered trademark) GT-401, エ ポ リ ー ド GT-403, エ ポ リ ー ド GT-301, エ ポ リ ー ド GT-302, セ ロ キ サ イ ド (registered trademark) 2021, セ ロ キ サ イ ド 3000, 1001, 1002, 1003, 1004, 1007, 1009, 1010, 828, 807, 152, 154, 180S75, 871, 872, EPPN201, EPPN202, EOCN-102, EOCN-103S, EOCN-104S, EOCN-1020, EOCN-1025, EOCN-1027, デ ナ コ ー ル (registered trademark) EX-252, デ ナ コ ー ル EX-611, デ ナ コ ー ル EX-612, デ ナ コ ー ル EX-614, デ ナ コ ー ル EX-622, デ ナ コ ー ル EX-411, デ ナ コ ー ル EX-512, ダ イ セ ル (registered trademark) EX-252, ナ ガ セ ケ ム テ ッ ク ス (strain), デ ナ コ ー ル EX-522, デ ナ コ ー ル EX-421, デ ナ コ ー ル EX-313, デ ナ コ ー ル EX-314, デ ナ コ ー ル EX-321, CY175, CY177, CY179, CY182, CY184, CY192 made by BASF ジ ャ パ ン (strain), エ ピ ク ロ ン 200, エ ピ ク ロ ン 400, エ ピ ク ロ ン 7015, エ ピ ク ロ ン 835LV, and エ ピ ク ロ ン 850CRP made by DIC (strain).

as the compound having at least 2 epoxy groups, a polymer compound may also be used. The polymer compound is not particularly limited as long as it is a polymer having at least 2 epoxy groups, and can be produced by addition polymerization using an addition polymerizable monomer having an epoxy group, or by reaction of a polymer having a hydroxyl group with a compound having an epoxy group such as epichlorohydrin or glycidyl tosylate. Examples of the polymer having at least 2 epoxy groups include addition polymers such as polyglycidyl acrylate, a copolymer of glycidyl methacrylate and ethyl methacrylate, a copolymer of glycidyl methacrylate and 2-hydroxyethyl methacrylate, and condensation polymers such as epoxy novolac. The weight average molecular weight of the polymer compound is, for example, 300 to 200,000. The weight average molecular weight is a value obtained by GPC using polystyrene as a standard sample.

As the compound having at least two epoxy groups, an epoxy resin having an amino group may be used. Examples of such epoxy resins include YH-434 and YH-434L (manufactured by NIKIRIZED エ ポ キ シ Co., Ltd.).

Examples of the compound having at least 2 blocked isocyanate groups include タ ケ ネ ー ト [ registered trademark ] B-830, タ ケ ネ ー ト B-870N manufactured by Mitsui chemical Co., Ltd., and VESTAN [ registered trademark ] -B1358/100 manufactured by エ ボ ニ ッ ク デ グ サ.

These compounds may be used alone or in combination of two or more.

When the crosslinkable compound is used, the content of the crosslinkable compound is, for example, 1 to 80% by mass, preferably 5 to 60% by mass, based on the content of the resin. When the content of the crosslinkable compound is too small or too large, the resistance of the formed film against a resist solvent may not be easily obtained.

The resist underlayer film forming composition of the present invention may contain a crosslinking catalyst (acid catalyst) as an optional component in order to promote the crosslinking reaction. As the crosslinking catalyst, for example, a sulfonic acid compound, a carboxylic acid compound, or a thermal acid generator can be used. Examples of the sulfonic acid compound include p-toluenesulfonic acid, pyridine-p-toluenesulfonic acid salt, pyridine-trifluoromethanesulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, pyridine-4-hydroxybenzenesulfonic acid salt, n-dodecylbenzenesulfonic acid, 4-nitrobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, trifluoromethanesulfonic acid, and camphorsulfonic acid. Examples of the carboxylic acid compound include salicylic acid, citric acid, benzoic acid, and hydroxybenzoic acid. Examples of the thermal acid generator include K-PURE [ registered trademark ] CXC-1612, K-PURE CXC-1614, K-PURE TAG-2172, K-PURE TAG-2179, K-PURE TAG-2678, K-PURE TAG2689, K-PURE TAG2700 (manufactured by King Industries Co., Ltd.), and SI-45, SI-60, SI-80, SI-100, SI-110 and SI-150 (manufactured by Sanxin chemical Industries, Ltd.).

These crosslinking catalysts may be used in 1 kind or in combination of 2 or more kinds. When the crosslinking catalyst is used, the content thereof is, for example, 0.1 to 20% by mass, preferably 1 to 10% by mass, based on the content of the resin.

The resist underlayer film forming composition of the present invention may contain a surfactant as an optional component in order to improve coatability to a substrate. Examples of the surfactant include nonionic surfactants such as polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether and polyoxyethylene oleyl ether, polyoxyethylene alkylallyl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene/polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate and sorbitan tristearate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate and polyoxyethylene sorbitan tristearate, and the like エ フ ト ッ プ (registered trademark) EF301, エ フ ト ッ プ EF303, エ フ ト ッ プ EF352 (manufactured by Mitsubishi マ テ リ ア ル Kabushiki Kaisha), メ ガ フ ァ ッ ク (registered trademark) F171, メ ガ フ ァ ッ ク F173, メ ガ フ ァ ッ ク R-30, メ ガ フ ァ ッ ク R-30N, メ ガ フ ァ ッ ク R-40-LM (manufactured by DIC Kabushiki Kaisha), フ ロ ラ ー ド FC430, フ ロ ラ ー ド FC431 (manufactured by Sumitomo ス リ ー エ ム Co., Ltd.), ア サ ヒ ガ ー ド (registered trademark) AG710, サ ー フ ロ ン (registered trademark) S-382, サ ー フ ロ ン SC101, サ ー フ ロ ン SC102, サ ー フ ロ ン SC103, サ ー フ ロ ン SC104, サ ー フ ロ ン SC105, サ ー フ ロ ン SC106 (manufactured by Asahi glass Co., Ltd.), a fluorine-based surfactant, and an organosiloxane polymer KP341 (manufactured by shin-Etsu chemical Co., Ltd.). These surfactants may be added alone or in combination of 2 or more.

When the surfactant is used, the content of the surfactant is, for example, 0.01 to 5% by mass, preferably 0.1 to 3% by mass, based on the content of the resin.

The resist underlayer film forming composition of the present invention can be prepared by dissolving the above components in an appropriate solvent, and can be used in a uniform solution state. As such a solvent, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethyl acetate, methyl acetate, ethyl acetate, and the like can be used, Butyl acetate, ethyl lactate, butyl lactate, N-dimethylformamide, N-dimethylacetamide, and N-methylpyrrolidone. These solvents may be used alone or in combination of 2 or more. Further, a high boiling point solvent such as propylene glycol monobutyl ether, propylene glycol monobutyl ether acetate, or the like may be mixed with these solvents and used.

The prepared composition is preferably used after filtration using a filter having a pore size of, for example, 0.2 μm, 0.1 μm or 0.05 μm. The resist underlayer film forming composition of the present invention is also excellent in long-term storage stability at room temperature.

The following describes a pattern forming method using the resist underlayer film forming composition of the present invention.

By the pattern forming method of the present invention, a pattern can be formed on a surface of a semiconductor substrate, an inorganic film on a semiconductor substrate, or the like.

Examples of the semiconductor substrate to which the resist underlayer film forming composition of the present invention is applied include silicon substrates, germanium substrates, and compound semiconductor wafers such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride. In the case of using a semiconductor substrate having an inorganic film formed on the surface thereof, the inorganic film is formed by, for example, an ALD (atomic layer deposition) method, a CVD (chemical vapor deposition) method, a reactive sputtering method, an ion plating method, a vacuum evaporation method, or a spin-on-glass (SOG) method. Examples of the inorganic film include a polysilicon film, a silicon oxide film, a silicon nitride film, a BPSG (Boro-phosphate Glass) film, a titanium nitride oxide film, a tungsten film, a gallium nitride film, and a gallium arsenide film.

The composition of the present invention is applied to the substrate having the recessed portion by an appropriate application method such as a spin coater or a coater, and then baked by a heating means such as a hot plate to form a resist underlayer film. The baking conditions are appropriately selected from the baking temperature of 80 to 350 ℃ and the baking time of 0.3 to 10 minutes. Preferably, the baking temperature is 120-300 ℃, and the baking time is 0.5-5 minutes. The film thickness of the resist underlayer film is, for example, 0.005 to 3.0. mu.m, for example, 0.01 to 0.1. mu.m, or 0.05 to 0.5. mu.m.

If the temperature during baking is lower than the above range, crosslinking may be insufficient, and resistance of the formed resist underlayer film to a resist solvent or an aqueous hydrogen peroxide solution may not be easily obtained. On the other hand, when the temperature during baking is higher than the above range, the resist underlayer film may be decomposed by heat and mixed with the resist film.

Next, a resist film is formed on the resist underlayer film. The formation of the resist film can be performed by a general method, i.e., coating and baking of a photoresist solution onto the resist underlayer film.

The photoresist solution used for forming the resist film is not particularly limited as long as it is a photoresist solution that is sensitive to a light source used for exposure, and both negative and positive types can be used.

In forming a resist pattern, exposure is performed through a mask (reticle) for forming a predetermined pattern of the resist pattern. For the exposure, for example, a KrF excimer laser or an ArF excimer laser can be used. After Exposure, Post Exposure heat (Post Exposure Bake) is performed as necessary. The conditions for the "post-exposure heating" are appropriately selected from the heating temperature of 80 to 150 ℃ and the heating time of 0.3 to 10 minutes. Then, a resist pattern is formed through a step of developing with an alkaline developer.

Examples of the alkaline developing solution include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, and aqueous solutions of amines such as ethanolamine, propylamine and ethylenediamine. Further, a surfactant or the like may be added to these developer solutions. The developing conditions are appropriately selected from a developing temperature of 5 to 50 ℃ and a developing time of 10 to 300 seconds.

Then, the resist underlayer film is dry-etched using the formed resist pattern as a mask. In this case, the surface of the inorganic film is exposed when the inorganic film is formed on the surface of the semiconductor substrate to be used, and the surface of the semiconductor substrate is exposed when the inorganic film is not formed on the surface of the semiconductor substrate to be used.

Further, a desired pattern is formed by wet etching using an aqueous hydrogen peroxide solution with the resist underlayer film after dry etching (the resist pattern is also used in the case where the resist pattern remains on the resist underlayer film) as a mask (for example, in the case where the inorganic film is formed on the surface of the semiconductor substrate to be used, the desired pattern may be formed on the inorganic film, or in the case where the inorganic film is not formed on the surface of the semiconductor substrate to be used, the desired pattern may be formed on the surface of the semiconductor substrate). Examples of the chemical solution for wet etching include a substance exhibiting alkalinity, and examples thereof include an alkaline aqueous hydrogen peroxide solution in which an organic amine such as ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, or triethanolamine is mixed with an aqueous hydrogen peroxide solution to make the pH alkaline, and an acidic aqueous hydrogen peroxide solution in which an inorganic acid such as hydrochloric acid or sulfuric acid is mixed with an aqueous hydrogen peroxide solution. Further, a substance having an alkaline pH, for example, a substance obtained by mixing urea with hydrogen peroxide water and thermally decomposing urea by heating to generate ammonia, may be used as a chemical solution for wet etching. The use temperature of the aqueous alkaline hydrogen peroxide solution and the aqueous acidic hydrogen peroxide solution is desirably 25 to 90 ℃, and more desirably 40 to 80 ℃. The wet etching time is preferably 0.1 to 30 minutes, and more preferably 0.5 to 15 minutes.